The base unit of a DOMString. This indicates that
indexing on a DOMString occurs in units of 16 bits.
This must not be misunderstood to mean that a
DOMString can store arbitrary 16-bit units. A
DOMString is a character string encoded in UTF-16;
this means that the restrictions of UTF-16 as well as the other
relevant restrictions on character strings must be maintained. A
single character, for example in the form of a numeric character
reference, may correspond to one or two 16-bit units.
For more information, see [Unicode] and [ISO/IEC 10646].

The description given to various information items (for
example, attribute values of various types, but not including the
StringType CDATA) after having been processed by the XML processor.
The process includes stripping leading and trailing white space,
and replacing multiple space characters by one. See the definition
of tokenized type.